This invention relates to a shaft drive for at least one heald shaft of a weaving machine.
For shed building in weaving machines, as a rule, several heald shafts are provided, each having a plurality of mutually parallel-arranged healds. The warp yarns are passed through the yarn eyelets of the healds. For shed building, the heald shafts are moved very rapidly up and down. For this purpose shaft drives are provided which are designated as shaft machines or eccentric machines. Eccentric machines generate an upward and downward motion of the heald shafts from the rotary motion, making possible high weaving speeds. However, such eccentric machines are inflexible. The production of patterns or various textures is feasible only in a limited manner. For this reason shaft drives are widely used where a pawl coupling is provided between the drive shaft and the eccentric for generating the heald shaft motion.
Such a shaft machine is known, for example, from German Patent Document 697 02 039 T2. The pawl switching mechanism provided between the eccentric and the drive shaft is, for each heald shaft motion, that is, for an upward motion of the heald shaft or a downward motion thereof, switched on for one half revolution of the drive shaft. Such shaft machines are very flexible. However, for the functioning of the pawl switching mechanism of such a shaft machine it is required that the entire drive, including all driving and driven elements, as well as the heald shaft, must be stationary during the switching phase. Shaft machines according to the above patent document thus perform switching in a stationary (detent) state.
It is accordingly the object of the invention to provide a shaft drive having a pawl switching mechanism which, since it switches during motion, makes possible high working speeds.